I had an extra 45w power adapter in my office; which I used to use with my Macbook Air. So today, I mated it to my new i7 MBP15 and was expecting it not to work because of insufficient power. But it seems to work just fine. Is there any harm in using the 45w power adapter at work and the 85w adapter on the road\home? I'm assuming the 45w adapter just wont charge the battery as fast.